19 Spatial Operators

This chapter describes the operators that you can use when working with the spatial object data type. For an overview of spatial operators, including how they differ from spatial procedures and functions, see Section 1.9. Table 19-1 lists the main operators.

For an explanation of the topological relationships and the nine-intersection model used by Spatial, see Section 1.8.

For information about 3D support with Spatial operators (which operators do and do not consider all three dimensions in their computations), see Section 1.11.

Examples

The following example finds geometries that have the ANYINTERACT relationship with a query window (here, a rectangle with lower-left, upper-right coordinates 4,6, 8,8). (The example uses the definitions and data described in Section 2.1 and illustrated in Figure 2-1.)

For an explanation of the topological relationships and the nine-intersection model used by Spatial, see Section 1.8.

For information about 3D support with Spatial operators (which operators do and do not consider all three dimensions in their computations), see Section 1.11.

Examples

The following example finds geometries that have the CONTAINS relationship with a query window (here, a rectangle with lower-left, upper-right coordinates 2,2, 4,6). (The example uses the definitions and data described in Section 2.1 and illustrated in Figure 2-1.) In this example, only cola_a contains the query window geometry.

For an explanation of the topological relationships and the nine-intersection model used by Spatial, see Section 1.8.

For information about 3D support with Spatial operators (which operators do and do not consider all three dimensions in their computations), see Section 1.11.

Examples

The following example finds geometries that have the COVEREDBY relationship with a query window (here, a rectangle with lower-left, upper-right coordinates 1,1, 5,8). (The example uses the definitions and data described in Section 2.1 and illustrated in Figure 2-1.) In this example, only cola_a is covered by the query window geometry.

For an explanation of the topological relationships and the nine-intersection model used by Spatial, see Section 1.8.

For information about 3D support with Spatial operators (which operators do and do not consider all three dimensions in their computations), see Section 1.11.

Examples

The following example finds geometries that have the COVERS relationship with a query window (here, a rectangle with lower-left, upper-right coordinates 1,1, 4,6). (The example uses the definitions and data described in Section 2.1 and illustrated in Figure 2-1.) In this example, only cola_a covers the query window geometry.

For an explanation of the topological relationships and the nine-intersection model used by Spatial, see Section 1.8.

For information about 3D support with Spatial operators (which operators do and do not consider all three dimensions in their computations), see Section 1.11.

Examples

The following example finds geometries that have the EQUAL relationship with a query window (here, a rectangle with lower-left, upper-right coordinates 1,1, 5,7). (The example uses the definitions and data described in Section 2.1 and illustrated in Figure 2-1.) In this example, cola_a (and only cola_a) has the same boundary and interior as the query window geometry.

SDO_FILTER

Format

SDO_FILTER(geometry1, geometry2, param);

Description

Uses the spatial index to identify either the set of spatial objects that are likely to interact spatially with a given object (such as an area of interest), or pairs of spatial objects that are likely to interact spatially. Objects interact spatially if they are not disjoint.

This operator performs only a primary filter operation. The secondary filtering operation, performed by the SDO_RELATE operator, can be used to determine with certainty if objects interact spatially.

Keywords and Parameters

Value

Description

geometry1

Specifies a geometry column in a table. The column must be spatially indexed. Data type is SDO_GEOMETRY.

geometry2

Specifies either a geometry from a table or a transient instance of a geometry. (Specified using a bind variable or SDO_GEOMETRY constructor.) Data type is SDO_GEOMETRY.

param

Optionally specifies either or both of the min_resolution and max_resolution keywords. Data type is VARCHAR2.

The min_resolution keyword includes only geometries for which at least one side of the geometry's MBR is equal to or greater than the specified value. For example, min_resolution=10 includes only geometries for which the width or the height (or both) of the geometry's MBR is at least 10. (This keyword can be used to exclude geometries that are too small to be of interest.)

The max_resolution keyword includes only geometries for which at least one side of the geometry's MBR is less than or equal to the specified value. For example, max_resolution=10 includes only geometries for which the width or the height (or both) of the geometry's MBR is less than or equal to 10. (This keyword can be used to exclude geometries that are too large to be of interest.)

Returns

The expression SDO_FILTER(geometry1,geometry2) = 'TRUE' evaluates to TRUE for object pairs that are non-disjoint, and FALSE otherwise.

Usage Notes

The SDO_FILTER operator must always be used in a WHERE clause and the condition that includes the operator should be an expression of the form SDO_FILTER(arg1, arg2) = 'TRUE'.

geometry2 can come from a table or be a transient SDO_GEOMETRY object, such as a bind variable or SDO_GEOMETRY constructor.

If the geometry2 column is not spatially indexed, the operator indexes the query window in memory and performance is very good.

If two or more geometries from geometry2 are passed to the operator, the ORDERED optimizer hint must be specified, and the table in geometry2 must be specified first in the FROM clause.

If geometry1 and geometry2 are based on different coordinate systems, geometry2 is temporarily transformed to the coordinate system of geometry1 for the operation to be performed, as described in Section 6.10.1.

RLS Restriction:

If the DBMS_RLS.ADD_POLICY procedure has been used to add a fine-grained access control policy to a table or view, and if the specified policy function uses a spatial operator, the operator must be SDO_FILTER. No other spatial operators are supported in that context.

For information about 3D support with Spatial operators (which operators do and do not consider all three dimensions in their computations), see Section 1.11.

Examples

The following example selects the geometries that are likely to interact with a query window (here, a rectangle with lower-left, upper-right coordinates 4,6, 8,8). (The example uses the definitions and data described in Section 2.1 and illustrated in Figure 2-1.)

The following example is the same as the preceding example, except that it includes only geometries where at least one side of the geometry's MBR is equal to or greater than 4.1. In this case, only cola_a and cola_b are returned, because their MBRs have at least one side with a length greater than or equal to 4.1. The circle cola_d is excluded, because its MBR is a square whose sides have a length of 4.

The following example selects the GID values from the POLYGONS table where the GEOMETRY column objects are likely to interact spatially with the GEOMETRY column object in the QUERY_POLYS table that has a GID value of 1.

The following example selects the GID values from the POLYGONS table where the GEOMETRY column object is likely to interact spatially with the geometry stored in the aGeom variable.

Select A.Gid
FROM Polygons A
WHERE SDO_FILTER(A.Geometry, :aGeom) = 'TRUE';

The following example selects the GID values from the POLYGONS table where the GEOMETRY column object is likely to interact spatially with the specified rectangle having the lower-left coordinates (x1,y1) and the upper-right coordinates (x2, y2).

The following example selects the GID values from the POLYGONS table where the GEOMETRY column object is likely to interact spatially with any GEOMETRY column object in the QUERY_POLYS table. In this example, the ORDERED optimizer hint is used and the QUERY_POLYS (geometry2) table is specified first in the FROM clause, because multiple geometries from geometry2 are involved (see the Usage Notes).

For an explanation of the topological relationships and the nine-intersection model used by Spatial, see Section 1.8.

For information about 3D support with Spatial operators (which operators do and do not consider all three dimensions in their computations), see Section 1.11.

Examples

The following example finds geometries that have the INSIDE relationship with a query window (here, a rectangle with lower-left, upper-right coordinates 5,6, 12,12). (The example uses the definitions and data described in Section 2.1 and illustrated in Figure 2-1.) In this example, only cola_d (the circle) is inside the query window geometry.

SDO_JOIN

Performs a spatial join based on one or more topological relationships.

Keywords and Parameters

Value

Description

table_name1

Name of the first table to be used in the spatial join operation. The table must have a column of type SDO_GEOMETRY. Data type is VARCHAR2.

column_name1

Name of the spatial column of type SDO_GEOMETRY in table_name1. A spatial R-tree index must be defined on this column. Data type is VARCHAR2.

table_name2

Name of the second table to be used in the spatial join operation. (It can be the same as or different from table_name1. If table_name2 is the same as table_name1, see "Optimizing Self-Joins" in this section.) The table must have a column of type SDO_GEOMETRY. Data type is VARCHAR2.

column_name2

Name of the spatial column of type SDO_GEOMETRY in table_name2. A spatial R-tree index must be defined on this column. Data type is VARCHAR2.

params

Optional parameter string of keywords and values; available only if mask=ANYINTERACT. Determines the behavior of the operator. See Table 19-3 in the Usage Notes for information about the available keywords. Data type is VARCHAR2. Default is NULL.

preserve_join_order

Optional parameter to specify if the join order is guaranteed to be preserved during processing of the operator. If the value is 0 (the default), the order of the tables might be changed; if the value is 1, the order of the tables is not changed. Data type is NUMBER. Default is 0.

table1_partition

Name of the table partition in table_name1. Must be specified if the table has a partitioned spatial index; must be null if the table does not have a partitioned spatial index. (For information about using partitioned spatial indexes, see Section 5.1.3.) Data type is VARCHAR2. Default is null.

table2_partition

Name of the table partition in table_name2. Must be specified if the table has a partitioned spatial index; must be null if the table does not have a partitioned spatial index. (For information about using partitioned spatial indexes, see Section 5.1.3.) Data type is VARCHAR2. Default is null.

Returns

SDO_JOIN returns an object of SDO_ROWIDSET, which consists of a table of objects of SDO_ROWIDPAIR. Oracle Spatial defines the type SDO_ROWIDSET as:

In the SDO_ROWIDPAIR definition, rowid1 refers to a rowid from table_name1, and rowid2 refers to a rowid from table_name2.

Usage Notes

SDO_JOIN is technically not an operator, but a table function. (For an explanation of table functions, see Oracle Database PL/SQL Language Reference.) However, it is presented in the chapter with Spatial operators because its usage is similar to that of the operators, and because it is not part of a package with other functions and procedures.

This table function is recommended when you need to perform full table joins.

The geometries in column_name1 and column_name2 must have the same SRID (coordinate system) value and the same number of dimensions.

For best performance, use the /*+ ORDERED */ optimizer hint, and specify the SDO_JOIN table function first in the FROM clause.

If a table is version-enabled (using the Workspace Manager feature), you must specify the <table_name>_LT table created by Workspace Manager. For example, if the COLA_MARKETS table is version-enabled and you want to perform a spatial join operation on that table, specify COLA_MARKETS_LT (not COLA_MARKETS) with the SDO_JOIN table function. (However, for all other Spatial functions, procedures, and operators, do not use the <table_name>_LT name.)

The topological relationship of interest.Valid values are 'mask=<value>' where <value> is one or more of the mask values valid for the SDO_RELATE operator (TOUCH, OVERLAPBDYDISJOINT, OVERLAPBDYINTERSECT, EQUAL, INSIDE, COVEREDBY, CONTAINS, COVERS, ANYINTERACT, ON), or FILTER, which checks if the MBRs (the filter-level approximations) intersect. Multiple masks are combined with the logical Boolean operator OR (for example, 'mask=inside+touch'); however, FILTER cannot be combined with any other mask.

If this parameter is null or contains an empty string, mask=FILTER is assumed.

distance

Specifies a numeric distance value that is added to the tolerance value (explained in Section 1.5.5) before the relationship checks are performed. For example, if the tolerance is 10 meters and you specify 'distance=100 unit=meter', two objects are considered to have spatial interaction if they are within 110 meters of each other.If you specify distance but not unit, the unit of measurement associated with the data is assumed.

unit

Specifies a unit of measurement to be associated with the distance value (for example, 'distance=100 unit=meter'). See Section 2.10 for more information about unit of measurement specification. If you specify unit, you must also specify distance.Data type is VARCHAR2. Default = unit of measurement associated with the data. For geodetic data, the default is meters.

Before you call SDO_JOIN, you must commit any previous DML statements in your session. Otherwise, the following error will be returned: ORA-13236: internal error in R-tree processing: [SDO_Join in active txns not supported]

For information about 3D support with Spatial operators (which operators do and do not consider all three dimensions in their computations), see Section 1.11.

Optimizing Self-Joins

If you are performing a self-join (that is, if table_name1 and table_name2 specify the same table), you can improve the performance by optimizing the self-join.

If SDO_JOIN is called without a mask (for example, ANYINTERACT) or distance specification, it compares only the index structure of the two geometry columns being joined. This can quickly identify geometry pairs that are "likely" to interact. If SDO_JOIN is called with a mask or distance specification, after the index is used to identify geometry pairs that are likely to interact, geometry coordinates are also compared to see if the geometry pairs actually do interact. Coordinate comparison is the most expensive part of the SDO_JOIN operation.

In a self-join, where the same geometry column is compared to itself, each geometry pair is returned twice in the result set. For example:

For the geometry pair with ID values (1,2), the pair (2,1) is also returned. The undesired effect in SDO_JOIN is that the coordinates of the same geometry pair are compared twice, instead of once.

ID pairs that are equal are returned twice. For example, a table with 50,000 rows will return ID pair (1,1) twice, ID pair (2,2) twice, and so on. This is also an undesired effect.

When calling SDO_JOIN in a self-join scenario, you can eliminate the undesired effects by eliminating duplicate comparison of geometry pairs and all coordinate comparisons where the ID values of the pairs match. This optimization uses SDO_JOIN for the primary filter only, and calls the SDO_GEOM.RELATE function to compare geometry coordinates. The following statement accomplishes this optimization by adding "AND b.rowid < c.rowid" as a predicate to the WHERE clause.

In the preceding example, It is very important that AND b.rowid < c.rowid be before the call to SDO_GEOM.RELATE in the WHERE clause. This will omit the undesired scenarios for the invocation of the SDO_GEOM.RELATE function. Also, note that the example uses the ORDERED and USE_NL hints, and that the execution plan does not contain TABLE ACCESS FULL or HASH JOIN.

Cross-Schema Invocation of SDO_JOIN

You can invoke the SDO_JOIN table function on an indexed table that is not in your schema, if you have been granted SELECT access to both the spatial table and to the index table for the spatial index that was created on the spatial table. To find the name of the index table for a spatial index, query the SDO_INDEX_TABLE column in the USER_SDO_INDEX_METADATA view. For example, the following statement returns the name of the index table for the COLA_MARKETS_IDX spatial index:

Assume that user A owns spatial table T1 (with index table MDRT_F9AA$), and that user B owns spatial table T2 and wants to join geometries from both T1 and T2. Assume also that the geometry column in both tables is named GEOMETRY.

User A or a suitably privileged user must connect as user A and execute the following statements:

GRANT select on T1 to B;
GRANT select on MDRT_F9AA$ to B;

User B can now connect and execute an SDO_JOIN query, such as the following:

The following example joins the COLA_MARKETS table with itself to find, for each geometry, all other geometries that have any spatial interaction with it. (The example uses the definitions and data from Section 2.1.) In this example, rowid1 and rowid2 correspond to the names of the attributes in the SDO_ROWIDPAIR type definition. Note that in the output, cola_d (the circle in Figure 2-1) interacts only with itself, and not with any of the other geometries.

SDO_NN

Uses the spatial index to identify the nearest neighbors for a geometry.

Keywords and Parameters

Value

Description

geometry1

Specifies a geometry column in a table. The column must be spatially indexed. Data type is SDO_GEOMETRY.

geometry2

Specifies either a geometry from a table or a transient instance of a geometry. The nearest neighbor or neighbors to geometry2 will be returned from geometry1. (geometry2 is specified using a bind variable or SDO_GEOMETRY constructor.) Data type is SDO_GEOMETRY.

param

Determines the behavior of the operator. The available keywords are listed in Table 19-4. If you do not specify this parameter, the operator returns all rows in increasing distance order from geometry2. Data type is VARCHAR2.

number

If the SDO_NN_DISTANCE ancillary operator is included in the call to SDO_NN, specifies the same number used in the call to SDO_NN_DISTANCE. Data type is NUMBER.

Specifies the number of distance units after which to stop searching for nearest neighbors. If you do not also specify the unit keyword, the default is the unit of measurement associated with the data. Data type is NUMBER.

For example: 'distance=10 unit=mile'

sdo_batch_size

Specifies the number of rows to be evaluated at a time when the SDO_NN expression may need to be evaluated multiple times in order to return the desired number of results that satisfy the WHERE clause. Available only when an R-tree index is used. If you specify sdo_batch_size=0 (or if you omit the param parameter completely), Spatial calculates a batch size suited to the result set size. See the Usage Notes and Examples for more information. Data type is NUMBER.

For example: 'sdo_batch_size=10'

sdo_num_res

If sdo_batch_size is not specified, specifies the number of results (nearest neighbors) to be returned. If sdo_batch_size is specified, this keyword is ignored; instead, use the ROWNUM pseudocolumn to limit the number of results. If neither sdo_batch_size nor sdo_num_res is specified, this is equivalent to specifying sdo_batch_size=0. See the Usage Notes and Examples for more information. Data type is NUMBER.

For example: 'sdo_num_res=5'

unit

If the distance keyword or the SDO_NN_DISTANCE ancillary operator is included in the call to SDO_NN, specifies the unit of measurement: a quoted string with unit= and an SDO_UNIT value from the MDSYS.SDO_DIST_UNITS table. See Section 2.10 for more information about unit of measurement specification. Data type is VARCHAR2. Default = unit of measurement associated with the data. For geodetic data, the default is meters.

For example: 'unit=KM'

Returns

This operator returns the sdo_num_res number of objects from geometry1 that are nearest to geometry2 in the query. In determining how near two geometry objects are, the shortest possible distance between any two points on the surface of each object is used.

Usage Notes

The operator is disabled if the table does not have a spatial index or if the number of dimensions for the query window does not match the number of dimensions specified when the index was created.

The operator must always be used in a WHERE clause, and the condition that includes the operator should be an expression of the form SDO_NN(arg1, arg2, '<some_parameter>') = 'TRUE'.

The operator can be used in two ways:

If all geometries in the layer are candidates, use the sdo_num_res keyword to specify the number of geometries returned.

The sdo_num_res keyword is especially useful when you are concerned only with proximity (for example, the three closest banks, regardless of bank name).

If any geometries in the table might be nearer than the geometries specified in the WHERE clause, use the sdo_batch_size keyword and use the WHERE clause (including the ROWNUM pseudocolumn) to limit the number of geometries returned.

The sdo_batch_size keyword is especially useful when you need to consider one or more columns from the same table as the nearest neighbor search column in the WHERE clause (for example, the three closest banks whose name contains MegaBank).

As an example of the sdo_batch_size keyword, assume that a RESTAURANTS table contains different types of restaurants, and you want to find the two nearest Italian restaurants to your hotel but only if they are within two miles. The query might look like the following:

In this example, the ROWNUM <=2 clause is necessary to limit the number of results returned to no more than 2 where CUISINE is Italian. However, if the sdo_batch_size keyword is not specified in this example, and if sdo_num_res=2 is specified instead of ROWNUM <=2, only the two nearest restaurants within two miles are considered, regardless of their CUISINE value; and if the CUISINE value of these two rows is not Italian, the query may return no rows.

The sdo_batch_size value can affect the performance of nearest neighbor queries. A good general guideline is to specify the number of candidate rows likely to satisfy the WHERE clause. Using the preceding example of a query for Italian restaurants, if approximately 20 percent of the restaurants nearest to the hotel are Italian and if you want 2 restaurants, an sdo_batch_size value of 10 will probably result in the best performance. On the other hand, if only approximately 5 percent of the restaurants nearest to the hotel are Italian and if you want 2 restaurants, an sdo_batch_size value of 40 would be better.

You can specify sdo_batch_size=0, which causes Spatial to calculate a batch size that is suitable for the result set size. However, the calculated batch size may not be optimal, and the calculation incurs some processing overhead; if you can determine a good sdo_batch_size value for a query, the performance will probably be better than if you specify sdo_batch_size=0.

If the sdo_batch_size keyword is specified, any sdo_num_res value is ignored. Do not specify both keywords.

Specify the number parameter only if you are using the SDO_NN_DISTANCE ancillary operator in the call to SDO_NN. See the information about the SDO_NN_DISTANCE operator in this chapter.

If two or more objects from geometry1 are an equal distance from geometry2, any of the objects can be returned on any call to the function. For example, if item_a, item_b, and item_c are nearest to and equally distant from geometry2, and if sdo_num_res=2, two of those three objects are returned, but they can be any two of the three.

If the SDO_NN operator uses a partitioned spatial index (see Section 5.1.3), the requested number of geometries is returned for each partition that contains candidate rows based on the query criteria. For example, if you request the 5 nearest restaurants to a point and the spatial index has 4 partitions, the operator returns up to 20 (5*4) geometries. In this case, you must use the ROWNUM pseudocolumn (here, WHERE ROWNUM <=5) to return the 5 nearest restaurants.

If geometry1 and geometry2 are based on different coordinate systems, geometry2 is temporarily transformed to the coordinate system of geometry1 for the operation to be performed, as described in Section 6.10.1.

SDO_NN is not supported for spatial joins.

In some situations the SDO_NN operator will not use the spatial index unless an optimizer hint forces the index to be used. This can occur when a query involves a join; and if the optimizer hint is not used in such situations, an internal error occurs. To prevent such errors, you should always specify an optimizer hint to use the spatial index with the SDO_NN operator, regardless of how simple or complex the query is. For example, the following excerpt from a query specifies to use the COLA_SPATIAL_IDX index that is defined on the COLA_MARKETS table:

However, if the column predicate in the WHERE clause specifies any nonspatial column in the table for geometry1 that has an associated index, be sure that this index is not used by specifying the NO_INDEX hint for that index. For example, if there was an index named COLA_NAME_IDX defined on the NAME column, you would need to specify the hints in the preceding example as follows:

(Note, however, that there is no index named COLA_NAME_IDX in the example in Section 2.1.)

If you join two or more tables with the SDO_NN operator and the sdo_num_res keyword, specify the LEADING hint for the outer table, USE_NL hint to have a nested loops join, and the INDEX hint for the inner table (the table with the spatial index). For example:

For information about 3D support with Spatial operators (which operators do and do not consider all three dimensions in their computations), see Section 1.11.

Examples

The following example finds the two objects from the SHAPE column in the COLA_MARKETS table that are nearest to a specified point (10,7). (The example uses the definitions and data described in Section 2.1 and illustrated in Figure 2-1.)

The following example uses the sdo_batch_size keyword to find the two objects (ROWNUM <=2), with a NAME value less than 'cola_d', from the SHAPE column in the COLA_MARKETS table that are nearest to a specified point (10,7). The value of 3 for sdo_batch_size represents a best guess at the number of nearest geometries that need to be evaluated before the WHERE clause condition is satisfied. (The example uses the definitions and data from Section 2.1.)

SDO_NN_DISTANCE

Returns the distance of an object returned by the SDO_NN operator. Valid only within a call to the SDO_NN operator.

Keywords and Parameters

Value

Description

number

Specifies a number that must be the same as the last parameter passed to the SDO_NN operator. Data type is NUMBER.

Returns

This operator returns the distance of an object returned by the SDO_NN operator. In determining how near two geometry objects are, the shortest possible distance between any two points on the surface of each object is used.

Usage Notes

SDO_NN_DISTANCE is an ancillary operator to the SDO_NN operator. It returns the distance between the specified geometry and a nearest neighbor object. This distance is passed as ancillary data to the SDO_NN operator. (For an explanation of how operators can use ancillary data, see the section on ancillary data in the chapter on domain indexes in Oracle Database Data Cartridge Developer's Guide.)

You can choose any arbitrary number for the number parameter. The only requirement is that it must match the last parameter in the call to the SDO_NN operator.

Use a bind variable to store and operate on the distance value.

Examples

The following example finds the two objects from the SHAPE column in the COLA_MARKETS table that are nearest to a specified point (10,7), and it finds the distance between each object and the point. (The example uses the definitions and data described in Section 2.1 and illustrated in Figure 2-1.)

1 is used as the number parameter for SDO_NN_DISTANCE, and 1 is also specified as the last parameter to SDO_NN (after 'sdo_num_res=2').

The column alias dist holds the distance between the object and the point. (For geodetic data, the distance unit is meters; for non-geodetic data, the distance unit is the unit associated with the data.)

The following example uses the sdo_batch_size keyword in selecting the two closest Italian restaurants to your hotel from a YELLOW_PAGES table that contains different types of businesses:

In the preceding query, the FIRST_ROWS hint enables the optimizer to improve performance by pushing the ORDER BY operation into the spatial index. :my_hotel can be either a bind variable or a literal value.

The FIRST_ROWS hint is also available to a local partitioned spatial index. In the preceding example, if the YELLOW_PAGES table is partitioned by name, the query will be executed as follows:

For each partition, the ORDER BY operation is processed using the spatial index until 10 rows are found.

After all partitions are completed, all rows found in the preceding step are sorted, and the top 10 rows are returned.

For an explanation of the topological relationships and the nine-intersection model used by Spatial, see Section 1.8.

For information about 3D support with Spatial operators (which operators do and do not consider all three dimensions in their computations), see Section 1.11.

Examples

The following example finds geometries that have the ON relationship with a query window (here, a rectangle with lower-left, upper-right coordinates 4,6, 8,8). (The example uses the definitions and data described in Section 2.1 and illustrated in Figure 2-1.) This example returns no rows because there are no line string geometries in the SHAPE column.

For an explanation of the topological relationships and the nine-intersection model used by Spatial, see Section 1.8.

For information about 3D support with Spatial operators (which operators do and do not consider all three dimensions in their computations), see Section 1.11.

Examples

The following example finds geometries that have the OVERLAPBDYDISJOINT relationship with a line string geometry (here, a horizontal line from 0,6 to 2,6). (The example uses the definitions and data described in Section 2.1 and illustrated in Figure 2-1.) In this example, only cola_a has the OVERLAPBDYDISJOINT relationship with the line string geometry.

For an explanation of the topological relationships and the nine-intersection model used by Spatial, see Section 1.8.

For information about 3D support with Spatial operators (which operators do and do not consider all three dimensions in their computations), see Section 1.11.

Examples

The following example finds geometries that have the OVERLAPBDYINTERSECT relationship with a query window (here, a rectangle with lower-left, upper-right coordinates 4,6, 8,8). (The example uses the definitions and data described in Section 2.1 and illustrated in Figure 2-1.) In this example, cola_a, cola_b, and cola_d have the OVERLAPBDYINTERSECT relationship with the query window geometry.

SDO_OVERLAPS

Format

SDO_OVERLAPS(geometry1, geometry2);

Description

Checks if any geometries in a table overlap (that is, have the OVERLAPBDYDISJOINT or OVERLAPBDYINTERSECT topological relationship with) a specified geometry. Equivalent to specifying the SDO_RELATE operator with 'mask=OVERLAPBDYDISJOINT+OVERLAPBDYINTERSECT'.

See the section on the SDO_RELATE operator in this chapter for information about the operations performed by this operator and for usage requirements.

For information about 3D support with Spatial operators (which operators do and do not consider all three dimensions in their computations), see Section 1.11.

Keywords and Parameters

Value

Description

geometry1

Specifies a geometry column in a table. The column must be spatially indexed. Data type is SDO_GEOMETRY.

geometry2

Specifies either a geometry from a table or a transient instance of a geometry. (Specified using a bind variable or SDO_GEOMETRY constructor.) Data type is SDO_GEOMETRY.

Returns

The expression SDO_OVERLAPS(geometry1,geometry2) = 'TRUE' evaluates to TRUE for object pairs that have the OVERLAPBDYDISJOINT or OVERLAPBDYINTERSECT topological relationship, and FALSE otherwise.

For an explanation of the topological relationships and the nine-intersection model used by Spatial, see Section 1.8.

Examples

The following example finds geometries that overlap a query window (here, a rectangle with lower-left, upper-right coordinates 4,6, 8,8). (The example uses the definitions and data described in Section 2.1 and illustrated in Figure 2-1.) In this example, three of the geometries in the SHAPE column overlap the query window geometry.

SDO_RELATE

Format

SDO_RELATE(geometry1, geometry2, param);

Description

Uses the spatial index to identify either the spatial objects that have a particular spatial interaction with a given object such as an area of interest, or pairs of spatial objects that have a particular spatial interaction.

This operator performs both primary and secondary filter operations.

Keywords and Parameters

Value

Description

geometry1

Specifies a geometry column in a table. The column must be spatially indexed. Data type is SDO_GEOMETRY.

geometry2

Specifies either a geometry from a table or a transient instance of a geometry. (Specified using a bind variable or SDO_GEOMETRY constructor.) Data type is SDO_GEOMETRY.

param

Specifies the mask keyword, and optionally either or both of the min_resolution and max_resolution keywords. The data type for this parameter is VARCHAR2.

The mask keyword specifies the topological relationship of interest. This is a required parameter. Valid mask keyword values are one or more of the following in the nine-intersection pattern: TOUCH, OVERLAPBDYDISJOINT, OVERLAPBDYINTERSECT, EQUAL, INSIDE, COVEREDBY, CONTAINS, COVERS, ANYINTERACT, ON. Multiple masks are combined with the logical Boolean operator OR, for example, 'mask=inside+touch'; however, see the Usage Notes for an alternative syntax using UNION ALL that may result in better performance. See Section 1.8 for an explanation of the nine-intersection relationship pattern.

The min_resolution keyword includes only geometries for which at least one side of the geometry's MBR is equal to or greater than the specified value. For example, min_resolution=10 includes only geometries for which the width or the height (or both) of the geometry's MBR is at least 10. (This keyword can be used to exclude geometries that are too small to be of interest.)

The max_resolution keyword includes only geometries for which at least one side of the geometry's MBR is less than or equal to the specified value. For example, max_resolution=10 includes only geometries for which the width or the height (or both) of the geometry's MBR is less than or equal to 10. (This keyword can be used to exclude geometries that are too large to be of interest.)

For backward compatibility, any additional keywords for the param parameter that were supported before release 10.1 will still work; however, the use of those keywords is discouraged and is not supported for new uses of the operator.

Returns

The expression SDO_RELATE(geometry1,geometry2, 'mask = <some_mask_val>') = 'TRUE' evaluates to TRUE for object pairs that have the topological relationship specified by <some_mask_val>, and FALSE otherwise.

Usage Notes

The operator is disabled if the table does not have a spatial index or if the number of dimensions for the query window does not match the number of dimensions specified when the index was created.

The operator must always be used in a WHERE clause, and the condition that includes the operator should be an expression of the form SDO_RELATE(arg1, arg2, 'mask = <some_mask_val>') = 'TRUE'.

geometry2 can come from a table or be a transient SDO_GEOMETRY object, such as a bind variable or SDO_GEOMETRY constructor.

If the geometry2 column is not spatially indexed, the operator indexes the query window in memory and performance is very good.

If two or more geometries from geometry2 are passed to the operator, the ORDERED optimizer hint must be specified, and the table in geometry2 must be specified first in the FROM clause.

If geometry1 and geometry2 are based on different coordinate systems, geometry2 is temporarily transformed to the coordinate system of geometry1 for the operation to be performed, as described in Section 6.10.1.

Unlike with the SDO_GEOM.RELATE function, DISJOINT and DETERMINE masks are not allowed in the relationship mask with the SDO_RELATE operator. This is because SDO_RELATE uses the spatial index to find candidates that may interact, and the information to satisfy DISJOINT or DETERMINE is not present in the index.

Although multiple masks can be combined using the logical Boolean operator OR, for example, 'mask=touch+coveredby', better performance may result if the spatial query specifies each mask individually and uses the UNION ALL syntax to combine the results. This is due to internal optimizations that Spatial can apply under certain conditions when masks are specified singly rather than grouped within the same SDO_RELATE operator call. (There are two exceptions, inside+coveredby and contains+covers, where the combination performs better than the UNION ALL alternative.) For example, consider the following query using the logical Boolean operator OR to group multiple masks:

The following considerations apply to relationships between lines and a multipoint geometry (points in a point cluster). Assume the example of a line and a multipoint geometry (for example, SDO_GTYPE = 2005) consisting of three points.

If none of the points has any interaction with the line, the relationship between the line and the point cluster is DISJOINT.

If one of the points is on the interior of the line and the other two points are disjoint, the relationship between the line and the point cluster is OVERLAPBDYDISJOINT.

If one of the points is on the boundary of the line (that is, if it is on the start point or end point of the line) and the other two points are disjoint, the relationship between the line and the point cluster is TOUCH.

If one of the points is on the boundary of the line (that is, if it is on the start point or end point of the line), another point is on the interior of the line, and the third point is disjoint, the relationship between the line and the point cluster is OVERLAPBDYDISJOINT (not OVERLAPBDYINTERSECT).

For information about 3D support with Spatial operators (which operators do and do not consider all three dimensions in their computations), see Section 1.11.

Examples

The following examples are similar to those for the SDO_FILTER operator; however, they identify a specific type of interaction (using the mask keyword), and they determine with certainty (not mere likelihood) if the spatial interaction occurs.

The following example selects the geometries that have any interaction with a query window (here, a rectangle with lower-left, upper-right coordinates 4,6, 8,8). (The example uses the definitions and data described in Section 2.1 and illustrated in Figure 2-1.)

The following example is the same as the preceding example, except that it includes only geometries where at least one side of the geometry's MBR is equal to or greater than 4.1. In this case, only cola_a and cola_b are returned, because their MBRs have at least one side with a length greater than or equal to 4.1. The circle cola_d is excluded, because its MBR is a square whose sides have a length of 4.

The following example selects the GID values from the POLYGONS table where the GEOMETRY column objects have any spatial interaction with the GEOMETRY column object in the QUERY_POLYS table that has a GID value of 1.

The following example selects the GID values from the POLYGONS table where a GEOMETRY column object has any spatial interaction with the specified rectangle having the lower-left coordinates (x1,y1) and the upper-right coordinates (x2, y2).

The following example selects the GID values from the POLYGONS table where the GEOMETRY column object has any spatial interaction with any GEOMETRY column object in the QUERY_POLYS table. In this example, the ORDERED optimizer hint is used and QUERY_POLYS (geometry2) table is specified first in the FROM clause, because multiple geometries from geometry2 are involved (see the Usage Notes).

For an explanation of the topological relationships and the nine-intersection model used by Spatial, see Section 1.8.

For information about 3D support with Spatial operators (which operators do and do not consider all three dimensions in their computations), see Section 1.11.

Examples

The following example finds geometries that have the TOUCH relationship with a query window (here, a rectangle with lower-left, upper-right coordinates 1,1, 5,7). (The example uses the definitions and data in Section 2.1 and illustrated in Figure 2-1.) In this example, only cola_b has the TOUCH relationship with the query window geometry.

SDO_WITHIN_DISTANCE

Uses the spatial index to identify the set of spatial objects that are within some specified distance of a given object, such as an area of interest or point of interest.

Keywords and Parameters

Value

Description

geometry1

Specifies a geometry column in a table. The column has the set of geometry objects that will be operated on to determine if they are within the specified distance of the given object (aGeom). The column must be spatially indexed. Data type is SDO_GEOMETRY.

aGeom

Specifies the object to be checked for distance against the geometry objects in geometry1. Specify either a geometry from a table (using a bind variable) or a transient instance of a geometry (using the SDO_GEOMETRY constructor). Data type is SDO_GEOMETRY.

params

A quoted string containing one or more keywords (with values) that determine the behavior of the operator. The remaining items (distance, max_resolution, min_resolution, querytype, and unit) are potential keywords for the params parameter. Data type is VARCHAR2.

distance

Specifies the distance value. If a coordinate system is associated with the geometry, the distance unit is assumed to be the unit associated with the coordinate system. This is a required keyword. Data type is NUMBER.

max_resolution

Includes only geometries for which at least one side of the geometry's MBR is less than or equal to the specified value. For example, max_resolution=10 includes only geometries for which the width or the height (or both) of the geometry's MBR is less than or equal to 10. (This keyword can be used to exclude geometries that are too large to be of interest.)

min_resolution

Includes only geometries for which at least one side of the geometry's MBR is equal to or greater than the specified value. For example, min_resolution=10 includes only geometries for which the width or the height (or both) of the geometry's MBR is at least 10. (This keyword can be used to exclude geometries that are too small to be of interest.)

querytype

Set 'querytype=FILTER' to perform only a primary filter operation. If querytype is not specified, both primary and secondary filter operations are performed (default). Data type is VARCHAR2.

unit

Specifies the unit of measurement: a quoted string with unit= and an SDO_UNIT value from the MDSYS.SDO_DIST_UNITS table (for example, 'unit=KM'). See Section 2.10 for more information about unit of measurement specification. Data type is NUMBER. Default = unit of measurement associated with the data. For geodetic data, the default is meters.

Returns

The expression SDO_WITHIN_DISTANCE(arg1, arg2, arg3) = 'TRUE' evaluates to TRUE for object pairs that are within the specified distance, and FALSE otherwise.

Usage Notes

The distance between two extended objects (nonpoint objects such as lines and polygons) is defined as the minimum distance between these two objects. The distance between two adjacent polygons is zero.

The operator is disabled if the table does not have a spatial index or if the number of dimensions for the query window does not match the number of dimensions specified when the index was created.

The operator must always be used in a WHERE clause and the condition that includes the operator should be an expression of the form:

The geometry column must have a spatial index built on it. If the data is geodetic, the spatial index must be an R-tree index.

SDO_WITHIN_DISTANCE is not supported for spatial joins. See Section 5.2.1.3 for a discussion on how to perform a spatial join within-distance operation.

For information about 3D support with Spatial operators (which operators do and do not consider all three dimensions in their computations), see Section 1.11.

Examples

The following example selects the geometries that are within a distance of 10 from a query window (here, a rectangle with lower-left, upper-right coordinates 4,6, 8,8). (The example uses the definitions and data described in Section 2.1 and illustrated in Figure 2-1. In this case, all geometries shown in that figure are returned.)

The following example is the same as the preceding example, except that it includes only geometries where at least one side of the geometry's MBR is equal to or greater than 4.1. In this case, only cola_a and cola_b are returned, because their MBRs have at least one side with a length greater than or equal to 4.1. The trapezoid cola_c is excluded, because its MBR has sides with lengths of 3 and 2; and the circle cola_d is excluded, because its MBR is a square whose sides have a length of 4.

The following example selects the GID values from the POLYGONS table where the GEOMETRY column object is within 10 distance units of the specified rectangle having the lower-left coordinates (x1,y1) and the upper-right coordinates (x2, y2).

The following example selects the GID values from the POLYGONS table where the GID value in the QUERY_POINTS table is 1 and a POLYGONS.GEOMETRY object is within 10 distance units of the QUERY_POINTS.GEOMETRY object.